gpg-interface, tag: add GPG_VERIFY_OMIT_STATUS flag

Functions that print git object information may require that the
gpg-interface functions be silent. Add GPG_VERIFY_OMIT_STATUS flag and
prevent print_signature_buffer from being called if flag is set.

Signed-off-by: Lukas Puehringer <luk.puehringer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gpg-interface.h

@@ -1,8 +1,9 @@
 #ifndef GPG_INTERFACE_H
 #define GPG_INTERFACE_H
 
-#define GPG_VERIFY_VERBOSE	1
-#define GPG_VERIFY_RAW		2
+#define GPG_VERIFY_VERBOSE		1
+#define GPG_VERIFY_RAW			2
+#define GPG_VERIFY_OMIT_STATUS	4
 
 struct signature_check {
 	char *payload;

tag.c

@@ -3,6 +3,7 @@
 #include "commit.h"
 #include "tree.h"
 #include "blob.h"
+#include "gpg-interface.h"
 
 const char *tag_type = "tag";
 
@@ -24,7 +25,9 @@ static int run_gpg_verify(const char *buf, unsigned long size, unsigned flags)
 
 	ret = check_signature(buf, payload_size, buf + payload_size,
 				size - payload_size, &sigc);
-	print_signature_buffer(&sigc, flags);
+
+	if (!(flags & GPG_VERIFY_OMIT_STATUS))
+		print_signature_buffer(&sigc, flags);
 
 	signature_check_clear(&sigc);
 	return ret;